The present invention relates to a dresser (also called a top plate or cover plate) for electromagnetic cookers.
Heretofore, dressers for electromagnetic cookers have been made using ceramic materials. At present, however, ceramic materials do not always possess satisfactory properties; for example, ceramic materials are apt to be cracked and to be molded. Particularly, as to moldability, ceramic materials cannot easily be formed into shapes having a holder portion or a frame portion for holding cookers such as pots and pans. Further, it is impossible effect integral molding with an outer frame or the like for engagement with a body portion, thus resulting in increase in the number of components of apparatus.
The use of a heat-resisting resin has been proposed for overcoming the above-mentioned drawbacks. As heat-resisting resins there are known silicone resins, FR-PET, polysulfone resins and polyphenylene oxide resins. Anyhow, as long as the prior art is followed, it cannot always be said that the characteristics required for the dresser are fully satisfied. Under the circumstances, a heat-resisting plastic material superior in performance has been desired.
For example, as to the dresser for an electromagnetic cooker, the following characteristics are required.
The dresser must withstand a continuous working temperature up to 200.degree. C.
The dresser must be as thin-walled as possible and have sufficient rigidity, and when a cooking vessel is placed thereon, the dresser must fully withstand the load of the vessel and is not deformed even at a high working temperature (100.degree.-200.degree. C.).
When food spilled during cooking adheres to the dresser, the dresser must permits easy removal of the food so that stain does not remain thereon.
It must be possible for the dresser to be colored beautifully to match the environment.
The dresser must be flame-retardant.
It is necessary for the dresser to have sufficient electrical characteristics.
Because of these severe characteristics required, ceramic materials have mainly been used for the dresser. However, with respect to the ceramic materials so far used, the following drawbacks have been pointed out.
Molding is difficult.
Coloring cannot always be performed as desired. In some case, it has been necessary to perform the coating of a glassy material. Because of difficult molding or difficult selection of various shapes, it is not always possible to make a satisfactory design in point of a holding characteristic of pots, pans, and the like.
Care must be exercised in handling because ceramic materials are apt to be cracked.
It is the object of the present invention to provide a dresser for electromagnetic cookers capable of eliminating all of the drawbacks mentioned above.